uz2work wrote:
While the 300/2.8 IS (either the original version or version II) is very close in size to the 400 DO, the weights are not as close. There is about a one pound difference between the 400 DO and the 300 version II, and about a 1 1/2 pound difference between the DO and 300 original version. If you have to add an extender to either of those 300 versions to get to the focal length of the 400 DO, the weight differences jump to about 1 1/2 pounds between the DO and the 300 version 2 and to about 2 pounds between the DO and the 300 original version. If you hold a 400 DO in one hand and either of the 300 versions in the other, the differences in weight are quite noticeable.

The 400mm DO is an indispensable lens for many occasions. I once took one to the Amazon basin in Ecuador. I was very glad to have a lighter lens when climbing in an out of canoes and scrambling up slippery embankments. Although, I did find that the contrast (with 1.4TC) was lower than my 500mm IS - this has been true for 2 versions rented from lensrentals.com. Perhaps, as you mention, the TC was not well matched with either.

one thing on the do to consider is that it is held together internally with an eclip or circlip, at reelfoot lake several weekends ago an acquaintance had his do body come apart - estimate was 2k to repair [used do lens out of warranty] they are hand holdable though and do allow pictures where the 400 f2.8 would be hard to use

I put it on my 5D3 and took a few snaps around the house and some shots outside the balcony. It was right after sunset so light was low and I had to use iso 3200 so the images do not work to critically judge the lens sharpness and optical qualities but they were enough for me to get a feel for the lens.

I noticed that the lens has a nice balance and its light enough to handhold for long periods of time. It was smaller than I thought although the hood is huge. Without the lens is pretty compact for its focal length.

The AF and IS felt really good. Pretty quiet IS system and engagement is quite smooth and I believe smoother than that in the 70-200's. I have yet to judge its effectiveness but Id say that with a 400mm lens one should use a sandbag or a monopod minimum for good results. I expect no miracles with the IS.

Like I mentioned, I had to use high iso's so IQ evaluation is pending but I did notice a jump in quality from f4 to f5.6. But again, no conclusions, might have been due to technique in that particular shot. I mostly shot wide open and the images were very good. AF was extremely accurate with my 5D3, wow, even when approaching minimum focusing distance.

Pending IQ testing, the lens is a great, compact package. But it really depends on how good is it at f4 because if I find the need to stop down to f5.6 then the extra expense makes much less sense since the 400 f5.6L is quite sharp and much much cheaper obviously. I do have the 1.4x II converter and will be testing it since a huge asset of the lens is that its fast enough to work with TC's.

Nothing negative intended here, but this question is a bit like asking should I buy a Ford F150 or a Toyota Camry. Both fine cars but very different uses. Depending what you need, one will be more satisfying than the other. I have to travel light but still want to do nature photography. For me the 400 DO was perfect. A bit of pp, and the images are wonderful. Do not read too much into the IQ comparisons, which while true, are probably practically insignificant for most persons who decide they want this lens's parameters (size, focal length, aperture, etc). Hike 6 miles with a 25 pound toddler in a pack on my back with the the DO? No problem, where's the moose! If I had only the 500 f4 or 400 2.8 I'd have left it behind. The do is a grand relatively small telephoto lens that travels well, but I suspect sales are hampered by the fact its price has been similar to the 500 f4 which is sharper and longer.

dgdg wrote:
I suspect sales are hampered by the fact its price has been similar to the 500 f4 which is sharper and longer.

When I bought my 400 DO several years ago, I paid $5200 for it, which was only $300 less than I paid for my 500/4 several years earlier. When I bought the DO, however, I was more than willing to pay the price premium in exchange for the mobility that a 4 pound 400 mm lens that could shoot at f4 would give me.

Over the years, though, the price difference between the DO and the 500/4 has increased significantly. When the original version 500/4 was discontinued, it was priced at about $2000 or more than the 400 DO price at that time, and, now, the 500/4 II is selling for about $4400 more than the 400 DO. Thus, while a few years ago it may have been the case that people were paying a price premium for the light weight of the 400 DO, with today's prices, the DO comes across to me like quite the bargain.

Sneakyracer wrote:
But it really depends on how good is it at f4 because if I find the need to stop down to f5.6 then the extra expense makes much less sense since the 400 f5.6L is quite sharp and much much cheaper obviously. I do have the 1.4x II converter and will be testing it since a huge asset of the lens is that its fast enough to work with TC's.

The f4 is of course a great advantage when you have less light. Compared to the f5.6, you have twice as much light for focusing and capturing the image. You would also have AF with a 2x TC on some bodies.

If you have to stop down to f5.6, then there would be no point in buying the DO.

Ok, I took quite a few test shots with the 400 DO this morning from my balcony. Infinity focus at a distant subject. I used a tripod. I used the lens wide open, with af on and off, with IS on and off, with IS mode 1 and 2 and also one stop down and with the 1.4x II wide open and one stop down. I did 18 combinations.

I came to the following conclusion.

Lens is as sharp wide open as stopped down in about 80% of the frame area. Stopping down gains just a hair more sharpness at the very edges of the frame. No big deal. The lens behaves similarly with the 1.4x. In fact, it was hard to tell if there was some image quality degradation by using the converter. For all practical purposes there was none really, maybe some increased CA and a tad more distortion. It was very little.

I did notice that the lens might not be truly f4. I think its about f4.5. Exposure was consistent with all settings (including when using the converter) but wide open the images were a touch darker overall (not vignetting).

So in conclusion, the lens has very consistent performance even wide open. There is really no need to stop down. You can use it at f4 all day with confidence. But, keep in mind that its a touch darker than f4. Its not much but its noticeable.

It has an awesome combination of size, weight and performance.

Would I choose it over the 300 2.8L IS v1?, I dunno. But at a pound lighter and slightly smaller size its a great tele for hiking and travel. (Forget about the 400 f2.8's for this).

PetKal wrote:
Markle acknowledged the gain in AF (and MF too ) a faster lens made, in his first sentence, just that by the second sentence in the post he might have had his train of thoughts derailed.

No, my train stayed on track. I have not seen anything stating the 400 DO focuses faster than the 400 f5.6. So if someone is shooting with the DO at f5.6 all the time, please tell me what the advantage is in having the DO.

Imagemaster wrote:
No, my train stayed on track. I have not seen anything stating the 400 DO focuses faster than the 400 f5.6. So if someone is shooting with the DO at f5.6 all the time, please tell me what the advantage is in having the DO.

The IS. If the 400 f5.6L had IS then it would be a much tougher decision. Also the AF on the 400 DO is really good. Have not tested the one on the 5.6L to compare though.

Also, I did have the 300 f4L IS and while its a good lens the 400 DO is MUCH better in all aspects. The 300 f4L is usable at f5.6 with the 1.4x II (wide open) but even though it gets better at f8 it is still no match for the 400's.

Imagemaster wrote:
No, my train stayed on track. I have not seen anything stating the 400 DO focuses faster than the 400 f5.6. So if someone is shooting with the DO at f5.6 all the time, please tell me what the advantage is in having the DO.

We have gone thru that many times, and you apparently have not been paying attention.

Imagemaster wrote:
If you have to stop down to f5.6, then there would be no point in buying the DO.

But I regularly do use my 400 DO wide open. When I do stop down, it isn't for image quality improvement, but it is because I want to increase depth of field. An f4 lens, at least, gives you the option of shooting at f4 when the situation can benefit from higher shutter speed, more depth of field, etc. No matter how hard I try, I can't make an f5.6 lens work at f4.

Imagemaster wrote:
I have not seen anything stating the 400 DO focuses faster than the 400 f5.6. So if someone is shooting with the DO at f5.6 all the time, please tell me what the advantage is in having the DO.

Since I sold my 400/5.6 before I got the DO, I can't make a direct comparison, but I do know that the DO jumps into focus about as fast as any lens that I've used, and, as pointed out by Sneakyracer, the IS is a big plus for the DO.

The AF drive speed of 400 DO is very similar to 400 f/5.6 prime, which is excellent.

However, 400 DO sheds twice as much light on the camera's AF sensors as 400 f/5.6 does.

Therefore, as ambient light level drops and/or target contrast fades, the camera with 400 DO will continue to AF well beyond the point at which the camera with 400 f/5.6 mounted on it ceased to AF dependably or can not AF at all.

However, even in good light the setups with 400 DO will tend to feel more AF responsive on real fast action. Similarly, my 300 f/2.8 IS MkI based setup responds to fast BIF even better than another setup based on 400 DO, although both lenses have a similar AF drive speed spec.

Are you paying $4600 more for IS? Or are you paying $4600 more for the ability to shoot at f4? Or are you paying $4600 more for an f4 lens that weighs only 4 pounds? Or, more likely, are you paying the extra money for the complete package of features that allows you to shoot successfully in a much wider range of situations than with the less expensive alternative. The price mark up seems a lot less unreasonable when you consider the full full package of features than it does when you only consider one of them.